Biomechanical Effects of Human Lumbar Discography: In Vitro Experiments and Their Finite Element Validation.

Study Design: An experimental and computational finite element analysis of human lumbar spine discography and its resulting effects on disk biomechanics.

Objective: To characterize the changes in stress and displacement of the human lumbar spine disks after puncture due to discography.

Summary Of Background Data: Discography of the intervertebral disk (IVD) may be used to diagnose pathology of the disk and determine whether it may be a source for chronic back pain.

Role for retinoid signaling in left-right asymmetric digestive organ morphogenesis.

The looping events that establish left-right asymmetries in the vertebrate gut tube are poorly understood. Retinoic acid signaling is known to impact left-right development in multiple embryonic contexts, although its role in asymmetric digestive organ morphogenesis is unknown. Here, we show that the genes for retinaldehyde dehydrogenase (RALDH2) and a retinoic acid hydroxylase (CYP26A1) are expressed in complementary patterns in the Xenopus gut during looping.